1. Field of the Invention
The present invention relates to a super electrochemical capacitor (typically EDLC) and, more particularly, to a super electrochemical capacitor including electrode plates having different quantities of electric charges, which increases electric charge and capacitance and raise a usable voltage range to thereby obtain high-voltage super capacitance.
2. Background of the Related Art
A capacitor or a condenser is generally classified into an electrostatic capacitor, an electrolytic capacitor and an electrochemical capacitor. The electrostatic capacitor includes a ceramic capacitor, a glass capacitor, a mica capacitor and so on and generally has a capacitance of approximately 1.0 to 10 μF. The electrolytic capacitor includes an aluminum electrolytic capacitor and a tantalum electrolytic capacitor. The electrolytic capacitor has a capacitance of approximately ten times the capacitance of the electrostatic capacitor.
The electrochemical capacitor, which is also called a super capacitor, includes an electric double layer capacitor (EDLC), a metal oxide pseudo capacitor and a hybrid super capacitor, which have an improved capacitance of approximately 1 mF to 3000 F.
In the super electrochemical capacitor, powder-type activated carbon is mixed with carbon black that is a conductive material and the mixture is attached onto a collector to form an electrode. Here, a binder is added to the electrode to bind the activated carbon, conductive material and collector to one another. Polysaccharide and fluoride-based binders are generally used as the binder. The binder is divided into a water-soluble binder and an organic binder depending on a solvent dissolving the binder. A process of forming the electrode depends on the kind of binder.
For the purpose of fabricating the super electrochemical capacitor, a method of forming a metal collector on a carbon fiber or an activated carbon fiber to fabricate a polarizing electrode, a method of compressing carbon paste on a conductive rubber or a metal collector, and a method of coating a slurry containing activated carbon powder on a metal collector have been developed.
FIG. 1 is a perspective view of a conventional capacitor 10, and FIG. 2 is a cross-sectional view of the conventional capacitor 10. Referring to FIGS. 1 and 2, two electrode plates 11a and 11b are formed to have the same size and spaced apart from each other by a dielectric layer or a collector layer 12 formed therebetween.
The collector layer 12 can use a condenser grade material, polymer film, or a hetero-structure complex of both of them. The capacitor 10 is fabricated in such a manner that the collector layer 12 is interposed between the two electrode plates 11a and 11b, and the collector layer 12 and electrode plate are alternately arranged repeatedly, as shown in FIG. 2.
Each of the electrode plates has the collector layer 12 on both sides thereof. The stacked electrode plates and collector layers are dipped in a dielectric solution. Halogen biphenyl was generally used as the dielectric solution.
However, the volume of the conventional capacitor should also be increased in order to increase the capacitance or voltage thereof because the two electrode plates of the capacitor have the same electric charge. Thus, a small-size capacitor cannot increase the electric charge and capacitance and make a usable voltage range large. Accordingly, a high-voltage super electrochemical capacitor cannot be realized. Furthermore, a small-sized capacitor having sufficient voltage and capacitance, which can comply with a technology trend toward the compact and slimness of electronic devices, could not be implemented.